In continued cooperation with Dr. Cook and his group, the synthesis of di- and polycyclic ring systems composed of cyclopentane rings has been developed further, with particular emphasis upon development of synthetic approaches to biologically active compounds of this type, and to a deepened understanding of the mechanisms of the reactions utilized. Cooperation with the colleagues in India in the field of chemistry of morphine and codeine is continuing. In cooperation with Professor Merlini and his associates the earlier studies on the chemistry of powerfully photosensitizing perylenequinones from certain molds has been continued. The complex stereochemistry of these mold metabolites presents unusual problems.